removal the outer boundary of bw image?

Hi all

i wrote this code

y=imread('..........bmp');
bw=im2bw(y);
b=bwboundaries(bw);
boundry=b{1};
imshow(bw);
hold on;
plot(boundry(:,2),boundry(:,1),'g');

i obtained this image http://postimage.org/image/91xxambx9/

now i need to remove the outer boundary in green color without any effect on the details inside this boundary , is this possible in matlab ? if it is possible how can this be done?

regards

[Walter Roberson]

Just don't plot the green ??

[mmm ssss]

no , is it what you understood from my question?

i want to remove this green boundary from also original image not from only the plotted figure , i means how to get rid of this green figure , eithout any affect on the details inside it.

thanks

[mmm ssss]

*without any affect on the details inside it

[Image Analyst]

Walter, I tried but I have no idea what he wants. Apparently it's not what you or I suggested even though both suggestions were valid possible approaches according to how he unclearly worded his question.

Answer 1

[Image Analyst]

Use morphological erosion

bw = imerode(bw, true(3));

[mmm ssss]

no , it is uncorrect because after morphological operation (skeletonization) , the outer boundary of the hand still exists.

i want to remove this green boundary from the original image also , not from the plotted one only.

[Image Analyst]

I did not say to do skeletonization. I said to do erosion. Erosion eats away at the outermost layer of white objects in a binary image. You could do the same thing by calling bwperim and subtracting that result from the original binary image- they're equivalent. I don't even know what you did because if you did either skeletonization or erosion, you would not have the outer layer of image remain.

[mmm ssss]

yes , but my target is to remove the green boundary now in order not to appear when i find the image skeleton , i means this green boundary must be removed without any effect on the inside detials , this will help in get good skeleton for the inside details without the green outer boundary

[mmm ssss]

http://www.2shared.com/photo/PZSrQfCA/analyat1.html

http://www.2shared.com/photo/qA7LujXu/Analyst1.html

http://www.2shared.com/photo/01vj7dQ-/analyst2.html

you can see the above images as an illustration to my question

[Image Analyst]

I guess I'm not sure what you want then. I told you how to find the outer layer of regions in a binary image (which is where you plotted the green pixels), but you say you don't want that. Therefore I fall back to what Walter says: Just don't plot the boundaries and you will have no green boundaries plotted in the overlay above your image.

[mmm ssss]

thanks , but this is not what i want

regards

[mmm ssss]

as we now that the hand has boundary and this must be removed not from only the plotted figure , but from original image also, for example if we said that we have a square and inside it there is 3 circle and one star , we want to remove only the square boundaries , without any affecting the boundaries of the star and boundaries of 3 circles.

[Image Analyst]

Yes, you can get the boundary coordinates from bwboundaries, from erosion, or from bwperim. Then just set those coordinates to zero in your original image and your binary image.

[mmm ssss]

how can i set them to zero , can you give me sample code please?

[mmm ssss]

mg=imread('E:\master_matlab\HandVein_DataSet\0010hv3.bmp');

level=graythresh(mg);

x=im2bw(mg,level);

figure,imshow(x);

BW2 = bwperim(~x);

figure,imshow(BW2);

now how can i remove the white border in BW2 image?

[mmm ssss]

and the obtain image mg without these border?

[mmm ssss]

*and the obtain image mg without these border?